Packaging materials

ABSTRACT

The use of a palladium-doped zeolite for the adsorption of volatile organic compounds is described wherein the zeolite has a CHA framework type and is polymer-bound. Such zeolites have been found to have particular utility as packaging materials for the adsorption of volatile organic compounds, such as those originating from organic matter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 16/604,344, filedApr. 10, 2018, which is the National Stage of International PatentApplication No. PCT/GB2018/050944, filed Apr. 10, 2018, which claimspriority to Great Britain Patent Application No. 1705796.9, filed Apr.11, 2017, the entire disclosures of each of which are incorporatedherein by reference for any and all purposes.

FIELD OF THE INVENTION

This invention relates to the adsorption of volatile organic compounds(VOCs) using polymer-bound palladium-doped zeolites. In particular, thepresent invention provides the use of polymer-bound palladium-dopedzeolites to adsorb VOCs originating from organic matter, and packagingmaterials and inks suitable for this purpose.

BACKGROUND TO THE INVENTION

The over-ripening or spoiling of fruit, vegetables and other organicmatter during transit or storage can lead to significant produce lossand wastage. This is an increasing issue for those involved in freshproduce supply chains which may involve long transit times and variableclimatic conditions. Modification of the atmosphere in which the organicmatter is stored has been shown to be an effective strategy to prolongproduce life. For example, alterations in oxygen and carbon dioxidelevels within produce packaging can reduce produce respiration rates andtherefore slow down the spoiling of fresh produce.

Other strategies involve the removal of volatile organic compounds(VOCs) from within, or surrounding, the produce packaging. VOCs aretypically emitted by the produce itself, or may be present in theenvironment in which the produce is stored or transported. The presenceof such VOCs can, for example, accelerate the spoiling of produce, leadto unwanted odours or tastes, or produce colour changes or other changesin appearance.

One such VOC is ethylene. Ethylene is a plant hormone and has a key rolein many physiological processes in plants. For example, exogenousethylene can initiate fruit ripening which in turn can lead to releaseof ethylene as the fruit ripens leading to high local concentrations.Other fresh produce types are also sensitive to ethylene even if theirown ethylene production is low. The rate of ethylene generation can be akey factor in determining local ethylene concentrations, and this ratevaries significantly between produce types. Excessive ethylene levelscan lead to, for example, the premature ripening of fruit andvegetables, the wilting of fresh flowers, and the loss of green colourand an increase in bitterness of vegetables.

The control of ambient ethylene levels has been found to be effective inprolonging the shelf-life of many horticultural products, and variousmethods of ethylene control are utilised commercially. Methods includethose based on ethylene adsorption and oxidation, for example the use ofpotassium permanganate.

Palladium-doped zeolites have been found to act as ethylene adsorbents.For example, it is described in WO2007/052074 (Johnson Matthey PublicLimited Company) that palladium-doped ZSM-5 may be used to adsorb VOCs,such as ethylene, which are derived from organic matter.

Adsorbents used to remove VOCs are typically used in the form of apowder or as granules. In the case of use within a fresh produce packagethe adsorbent material is typically incorporated into a label attachedto the inside of the package, or may be contained within a sachet, pador other insert located within the package.

WO2014207467A1 (Johnson Matthey Public Limited Company) describes awater-resistant composition for adsorbing VOCs comprisingpalladium-doped hydrogen ZSM-5 and at least one water soluble binder.Compositions are prepared and applied to Tyvek® paper.

It would be advantageous to incorporate the adsorbent materials intopackaging materials as an alternative to providing the adsorbent insidea sachet, pad or other type of insert. In this case the adsorbentmaterial would be more widely dispersed within the package and could beprotected from direct contact with water. Furthermore, if the adsorbentmaterial is combined with primary packaging there is no need for anadditional insert or inserts to be placed inside the packaging. Theseadvantages could lead to less adsorbent material being included, reducedpackaging material, and fewer processing steps.

WO2016181132A1 (Innovia Films Ltd, Food Freshness Technology HoldingsLtd) describes a film for use in a packaging structure which comprises acoating on the film surface which comprises a binder and a particulateprotuberent component able to remove VOCs. The examples describe the useof a palladium-doped zeolite as the protuberent component and ZSM-5 ismentioned.

The combination of adsorbent and polymeric materials remains achallenge, as binding of adsorbent materials with polymeric materialstypically leads to a significant loss of adsorbent capacity and/or rateof adsorption, leading to poor performance. Resulting materials may alsosuffer from low stability. There remains a need to develop additionalmaterials incorporating adsorbents which are suitable for use with freshproduce, for example as packaging films or other packaging materials.

SUMMARY OF THE INVENTION

It has been surprisingly found that palladium-doped zeolites with a CHAframework-type may be combined with polymeric materials and retain asignificant proportion of VOC adsorption capacity, whilst maintaining arate of removal such that the combined materials are suitable for use aspackaging materials with a range of produce types. It has also beenfound that stable polymeric films may be prepared which comprise thesezeolite materials. Such films and other packaging materials may providebenefits including the extension of shelf life and the reduction offresh produce spoilage.

Therefore, in a first aspect of the invention, there is provided the useof a palladium-doped zeolite for the adsorption of volatile organiccompounds, in particular volatile organic compounds originating fromorganic matter, wherein the zeolite has a CHA framework type and ispolymer-bound.

In a second aspect of the invention, there is provided a method foradsorbing volatile organic compounds, in particular volatile organiccompounds originating from organic matter, comprising the step ofcontacting the compounds with a zeolite with a CHA framework type andwhich is polymer-bound.

In a third aspect of the invention there is therefore provided apackaging material for the adsorption of volatile organic compounds, inparticular volatile organic compounds originating from organic matter,the packaging material comprising a palladium-doped zeolite, wherein thezeolite has a CHA framework type. Preferably, the polymeric material isa packaging film.

Preferably, the packaging materials comprise a polymer film layer andparticles of the zeolite are dispersed in the polymer film layer. Suchfilm layers are obtainable by a compounding and extrusion process and ithas been surprisingly found by the inventors that zeolites with a CHAframework type have an unexpectedly high retention of adsorptioncapacity despite the polymer processing conditions which are used toform the polymer film layer, which include high temperatures andgrinding of the adsorbent with the polymeric material.

The compounded mixture may be isolated as a masterbatch prior toextrusion. Isolating a masterbatch can help facilitate transportationand storage of the adsorbent material, and simplify manufacturing of thepackaging materials. Therefore, in a further aspect of the inventionthere is provided a masterbatch comprising a polymer and particles of apalladium-doped zeolite, wherein the zeolite has a CHA framework type.

Packaging materials may also be produced by the application of a coatingonto a surface of the packaging material, such as a polymer film, thecoating comprising a polymeric binder, and particles of the zeolite.Therefore, in another aspect of the invention there is provided an inkfor application to a packaging material, the ink comprisingpalladium-doped zeolite particles and a polymeric binder, wherein thezeolite has a CHA framework type.

The packaging materials as described herein may be used to form apackaging structure. The materials may be used to seal a packagingstructure, for example to seal a punnet, box or bottle, or may, forexample, form the majority of the packaging structure, such as in thecase of a bag or wrap.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the results of ethylene adsorption testing of polymer filmsincorporating Pd-doped zeolite particles with different framework types.

FIG. 2 shows the results of ethylene adsorption testing of 1% Pd-dopedchabazite in the form of a powder and incorporated into a multi-layerfilm.

FIG. 3 shows the results of ethylene adsorption testing of a LDPE filmincorporating 1% Pd-doped chabazite.

FIG. 4 shows the results of ethylene adsorption testing of a PVP coatingincorporating 1% Pd-doped chabazite applied to a polyamide film.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to polymer-bound zeolites with a CHA frameworktype and their utility for the adsorption of VOCs. The CHA three-lettercode represents a framework type in accordance with the “IUPACCommission on Zeolite Nomenclature” and/or the “Structure Commission ofthe International Zeolite Association”.

It will be understood that the zeolites may include regions in which theframework is a CHA/AEI mixture or intergrowth, however it is generallypreferred that the zeolite has a framework that does not include anintergrowth of CHA and another framework type.

The zeolite typically has a silica to alumina molar ratio (SAR) of lessthan or equal to 100:1, such as between 10:1 and 50:1, preferably 10:1to 40:1, more preferably 20:1 to 30:1.

The described zeolites have been found to retain a significantproportion of ethylene adsorption capacity when polymer-bound. The termpolymer-bound will be understood by the skilled person to mean that tothat the zeolite is embedded in or encapsulated by a polymeric material.Preferably, the zeolite material is encapsulated by a polymeric materialproviding protection from contact with water.

The zeolite framework may be counterbalanced by cations, such as bycations of alkali and/or alkaline earth elements (e.g. Na, K, Mg, Ca,Sr, and Ba), ammonium cations and/or protons. Preferably, the zeolite isin the hydrogen form.

The zeolite is doped with palladium, and typically comprises 0.1 to 10wt % palladium based on the total weight of doped zeolite, preferably0.2 to 2 wt %, 0.3 to 1.8 wt %, 0.3 to 1.6 wt %, 0.3 to 1.4 wt %, morepreferably 0.3 to 1.2 wt %, 0.4 to 1.2 wt %, 0.6 to 1.2 wt %, or 0.8 to1.2 wt %.

Such zeolites are typically prepared by incipient wetness impregnationusing a palladium nitrate solution, drying the particles, and thencalcining at a temperature between 450 and 750° C.

The zeolite particles may be dispersed in a polymer film. Suitablepolymeric materials include polyvinyl chlorides, polyethylenes,polypropylenes, ethylene-vinyl acetate co-polymers, polystyrenes,polybutylenes, polycarbonates, polyesters, polyethylene terephthalatesand mixtures, blends and co-polymers thereof. Preferably, the polymer isan ethylene vinyl acetate co-polymer, a low-density polyethylene, ahigh-density polypropylene, a polypropylene, or a high impactpolystyrene. More preferably, the polymer is an ethylene vinyl acetatecopolymer or low-density polyethylene

Preferably, polymers, or mixtures of polymers, are selected which havehigh gas permeability so that the polymeric material is not detrimentalto VOC adsorption rate. The gas permeation rate is a measure of theextent to which a material can act as a barrier to a gas. One known unitfor the gas permeation rate of a polymer is cubic centimetres of a gasat standard temperature and pressure passing through a one-micron film,with an area of a square metre, over a period of one hour, with apartial pressure differential of the gas of one standard atmosphere.This known unit is abbreviated as cm³.μm/m².h.atm. The gas permeationrate is temperature dependent. One known convention for testing of filmsis to test at 25° C. and 0% relative humidity (RH). The permeation ratefor a given polymer also depends on the gas itself. It has been foundthat the permeation rate of carbon dioxide is a good surrogate for VOCs,in particular ethylene. Therefore, preferably the polymer film layercomprises a polymer, or mixture of polymers, with a carbon dioxidepermeability rate of >1.00e+02 cm³.μm/m².h.atm at 25° C. and 0% RH, morepreferably >1.00e+04 cm³.μm/m².h.atm. The carbon dioxide transmissionrate through a film may be measured using standard methods such as ASTMF 2478 ‘Standard Test Method for the Determination of Carbon Dioxide GasTransmission Rate (CO₂TR) Through Barrier Materials Using An InfraredDetector’. The carbon dioxide permeation rate is the CO₂TR normalised tothe material thickness and pressure gradient.

Such films are obtainable by a polymer extrusion process, the processcomprising the steps of (i) compounding at least one polymer andparticles of a palladium-doped zeolite with a CHA framework type; (ii)extruding the compounded mixture to form the polymer film. The selectedpolymeric materials are compounded with the palladium-doped zeoliteparticles using, for example, a twin screw extruder. The films are thenproduced by extrusion, for example by blown film or cast film extrusion.

It has been found that the maintaining a relatively low temperatureduring the compounding and/or extrusion steps can be advantageous withregards to retention of VOC adsorption capacity of the zeolite material.Typically, the compounding and/or extrusion steps may be carried out ata temperature of less than 200° C., such as between 120° C. and 180° C.For example, if the polymer material is an ethylene-vinyl acetatecopolymer the temperature of the compounding and/or extrusion steps istypically between 120° C. and 180° C., preferably between 120° C. and170° C., more preferably between 120° C. and 150° C., even morepreferably between 120° C. and 140° C. If the polymer material is alow-density polyethylene then the temperature of the compounding and/orextrusion steps is typically between 150° C. and 190° C., preferablybetween 150° C. and 180° C., more preferably between 150° C. and 170° C.

It will be understood by the skilled person that the compounded mixturemay be isolated as a masterbatch prior to film formation. The compoundedmaterial is typically pelletized as part of this process. The formationof masterbatch may be advantageous, for example to facilitatetransportation of the adsorbent and to enable production of thepackaging films using standard polymer processing facilities.

The masterbatch typically contains zeolite particles in the range 1-50wt % based on the total weight of the masterbatch material.

Polymer films as described herein are then obtainable by extruding themasterbatch, with or without the addition of further polymeric materialdepending on the desired loading of palladium-doped zeolite in theformed film. Suitable extrusion processes include blown film or castfilm extrusion.

Typically, the extruded polymer film will have a thickness of between 2to 100 μm, preferably 5 to 30 μm. The palladium-doped zeolite particlesare dispersed in the polymer film, typically at a zeolite loading of 1to 50 wt % based on total weight of polymer film, preferably at azeolite loading of 1 to 10 wt % based on total weight of polymer film.

The zeolite material is preferably provided in the form of particles,which typically have a size (d50) of 1 μm to 25 μm, preferably 5 and 10μm. The particle size distribution of particles dispersed in the filmmay be measured, for example, by scanning electron microscopy.

As an alternative to dispersion in a polymer film, the zeolite particlesmay be incorporated in a coating on a surface of a packaging material,such as a polymer film, or a lid for a container, such as a bottle lidor the lid of a clamshell box, or a packaging insert, such as a strip orpad, for example a Tyvek® strip. Such a coating comprises a polymericbinder and zeolites particles.

The coating may be applied, for example, to the packaging materialsurface using a water-based ink which is then dried. In such cases awater-soluble binder may be used, for example a polvinylpyrrolidone.Preferably, the ink comprises a water-soluble binder and particles ofpalladium-doped zeolite with a CHA framework type in water. The weightratio of palladium-doped zeolite to water-soluble binder in the ink istypically 3:1 to 19:1.

The coating is applied to a suitable packaging material, for example apolymer film formed from a polyamide, a polyethylene, a polypropylene,an ethylene-vinyl acetate co-polymer, a polyethylene terephthalate, apolystyrene, or a mixture, blend or co-polymer thereof. Preferably, thepolymer film is an ethylene vinyl acetate, a low-density polyethylene, ahigh-density polypropylene, a biaxially orientated polypropylene,polyamide or a high impact polystyrene.

The zeolite material in the coating is preferably in the form ofparticles, which typically have a size (d50) of 1 μm to 25 μm,preferably 5 and 10 μm. The particle size distribution of particlesincluded in the coating composition may be measured, for example, bylaser diffraction, for example by generating a suspension of particlesin deionised water and measuring the particle size distribution using aMalvern Mastersizer 2000.

The zeolites as described herein may be used to generate packagingfilms. The packaging films may be a single polymer layer, or maycomprise a laminate structure of two or more layers which may be thesame or different materials.

In one arrangement, the packaging film comprises or consists essentiallyof a single layer of polymer film in which particles of the zeolite aredispersed.

In a further arrangement, the packaging film comprises a single polymerfilm layer which has a coating applied on one or both surfaces of thefilm, the coating comprising particles of the zeolite and a polymericbinder.

In another arrangement, the packaging film comprises two or more polymerfilm layers, the packaging film having at least one layer in which thezeolite particles are dispersed. It will be understood by the skilledperson that in the case in which the packaging films comprise at leastthree layers, the layer or layers in which the zeolite particles aredispersed is preferably an exterior layer of the packaging film. Suchpackaging films may be formed, for example, by an extrusion orlamination process.

In yet another arrangement, the packaging film comprises two or morepolymer film layers, at least one of which is provided with a coatingapplied to at least one outer surface of the packaging film, the coatingcomprising particles of the zeolite and a polymeric binder.

Typically, the packaging films will have a thickness of between 5 μm to200 μm, preferably 10 to 100 μm, more preferably 15 to 40 μm. If acoating is applied, then the coating layer has a typical thickness (i.e.the average binder thickness in the coating layer) of 0.1 to 5 μm.

The packaging film may additionally comprise a gas-permeable barrierlayer, for example a silicone rubber, or other synthetic or naturalrubber material, which may improve the stability of the packaging filmand which may be advantageous in particular for food or other consumablepackaging applications, for instance the gas-permeable barrier layer canprevent particulate additives included in the polymer matrix frommigrating to the film surface, and therefore prevent contact between theadditives and the packaging contents. The barrier layer may be appliedby a coating process, a lamination process or by extrusion during a filmblowing process.

The packaging films may additionally comprise an anti-fog additive. Suchadditives are known to those skilled in the art, and may comprise adetergent and/or a surfactant.

The zeolites and packaging materials as described herein may beadvantageously used for the adsorption of VOCs. The VOCs may be, forexample, plant growth regulators such as ethylene, odorous species suchas ammonia, or acetic acid, and other by-products of producedecomposition such as trimethylamine.

The zeolites and packaging materials as described herein may beadvantageously used for the adsorption of VOCs originating from organicmatter, such as fruit, vegetables, cut flowers, or other foodstuffs. TheVOC is typically ethylene. In particular, the zeolites and films may beused for the adsorption of ethylene originating from climactericproduce, such as bananas, avocados, nectarines, melons and pears whichrelease a burst of ethylene during ripening, accompanied by an increasein respiration. Other non-climacteric produce types which are sensitiveto ethylene include potatoes, onions, broccoli, cabbage and cut flowers.

Typically, the organic matter is contained in a packaging structureduring storage and transportation, such as a crate, bag, bottle, box orpunnet. The zeolites and packaging materials may therefore beadvantageously used to control ethylene levels within such packagingstructures.

The packaging materials may be used to seal the packaging structure, forexample to seal a punnet, bottle or a box, or may, for example, form themajority of the packaging structure, such as in the case of a bag, orpackaging film may be used to wrap produce or wrap containers ofproduce, such as boxes.

It will be understood by the skilled person that in the case ofmulti-layer or coated packaging films the layer incorporating zeoliteparticles, or the coating layer, is typically presented to the interiorof the packaging structure enabling the control of the atmosphericcomposition within the structure. It may be envisaged however that theoutermost layer of the packaging film may alternatively or in additionincorporate zeolite particles, or be coated with a layer incorporatingzeolite particles, in order to adsorb VOCs generated externally to thepackaging structure, for example during transportation.

The packaging structure may comprise a polymer film that is perforated,for example with holes or slits which are typically 50-500 μm indiameter or length as appropriate. Such perforations may be formed bylaser perforation. In use, the degree of perforation may be used tocontrol the gaseous composition within the packaging structure onceproduce has been placed inside, leading to a lower oxygen content. Sucha packaging structure may be known as modified atmosphere packaging.Both unmodified and modified atmosphere packaging structures may be usedwith packaging films as described herein.

It should be noted that the term “adsorbent” and “adsorption” as usedherein should not be construed as being limited to the uptake of VOCs toa particular route and includes the chemical conversion of VOCs intosecondary compounds. As used herein, the term “adsorbent” is synonymouswith “absorbent”.

The expression “consists essentially” as used herein limits the scope ofa feature to include the specified materials, and any other materials orsteps that do not materially affect the basic characteristics of thatfeature, such as for example minor impurities. The expression “consistsessentially of” embraces the expression “consisting of”.

Examples

The invention is now illustrated with the following non-limitingexamples:

Example Preparation of Palladium-Doped Zeolites 1% Pd-doped H-chabazite(SAR=22): Samples were prepared by incipient wetness impregnation. Pdnitrate (˜8%) solution was weighed out to give the desired weight % ofmetal on the zeolite. The Pd nitrate solution was then diluted withwater up to around 60-70% pore fill of the zeolite. The solution wasadded to the zeolite powder (obtained from Tosoh Corporation) using apipette and every few drops added the solution was manually stirred and‘wet lumps’ were broken up using a spatula to keep the sample ashomogenous as possible. The sample was then dried at 105° C. (2 hr) andthen calcined at a temperature of 500° C. for 2 hrs with a 10° C./minramp rate.

The samples of 1% Pd-doped H-ZSM-5 (SAR=23) and 0.4% Pd-doped H-betazeolite (SAR=28) were prepared according to the described method withthe following changes to conditions: (i) The Pd nitrate solution wasdiluted with water up to around 95% pore fill of the zeolite; (ii) thedrying time was 18 hr.

Example Preparation of Polymer Masterbatches Incorporating Pd-DopedZeolites

A twin screw extruder (Dr Collin) was used to compound Pd-doped zeoliteparticles with the selected polymer. Twin screw compounding speed was 20rpm with a set temperature between 120 and 180° C. The compoundedmaterial was then pelletised into a masterbatch.

Example 1—Preparation of Ethyl-Vinyl Acetate Films IncorporatingPd-Doped Zeolite Particles with Different Framework Types

A twin screw extruder (Dr Collin) was used to compound ethylene-vinylacetate (EVA FL00209) with Pd-doped zeolite particles with differentframework types as described above at a temperature of 130° C. Thezeolite and polymer addition rates were adjusted so as to result in afilm with around 1.5 wt % palladium-doped zeolite. The compoundedmixtures were then extruded through a blown film line to producemultilayer structures (20 μm), using the following conditions:

Inner layer (EVA):

Extrusion speed: 25 rpm

Temperature profile from feeding zone to die adaptor (° C.): 30, 130,130, 130, 130

Middle layer (EVA):

Extrusion speed: 25 rpm

Temperature profile from feeding zone to die adaptor (° C.): 30, 130,130, 130, 130

Outer layer (EVA+absorbent):

Extrusion speed: 50 rpm

Temperature profile (° C.) from feeding zone to die: 30, 130, 130, 130,130, 130, 130 and 130

The zeolite loading in the produced films was confirmed by an ash test.The test involved heating a sample of the films to 500° C. for 5 hours.The zeolite loading was then calculated using the formula:

Zeolite loading=Net ash/Net film*100%

According to the film ash test results, the tested film had a zeoliteloading as follows:

Pd-Chabazite-1.57 w %;

Pd-ZSM-5-1.45 w %;

Pd-beta-1.89 w %;

Testing of Polymer Films

A series of experiments were conducted to evaluate the ethylene removalperformance of different palladium-doped zeolites to compare theirperformance after incorporation into the polymer film vs as a powder.

Ethylene Uptake Measurement

A film containing ca. 0.2 g zeolite was prepared and placed into asealed 1990 ml jar. Ethylene gas was injected into the jar and reached500 ppm. The inner atmosphere in the jar was analysed at regularintervals. The concentration of ethylene was determined by GC analysis.Temperature and humidity in the jar were maintained at 5° C. and RH90˜95% during the test.

Results

FIG. 1 shows the results of ethylene adsorption testing. 1% Pd-chabazite(SAR 22) was found to remove ethylene continuously over the period ofthe study with a high removal rate, and with a particularly advantageousprofile in comparison with the other framework types tested.

Example 2—Comparison of the Ethylene Removal Capacity of the Multi-LayerPolymer Film Incorporating Pd-Doped Chabazite Particles and Pd-DopedChabazite Powder

0.2 g of 1% Pd-Chabazite powder and an EVA multilayer film incorporatedwith 0.199 g of 1% Pd-Chabazite powder were prepared as described inexample 1. The ethylene removal performance of both were evaluated inthe ethylene uptake test, at wet and low temperature conditions (5° C.and RH90˜95%), which can mimic food storage conditions. The ethyleneremoval performance of the multilayer film was shown in FIG. 2 . It wasfound the film retained around ca. 80% activity of the zeolite powder.

Example 3—Preparation and Testing of a LDPE Polymer Film

A twin screw extruder (Dr Collin) was used to compound low densitypolyethylene (Lupolen 3020H) with 1% Pd-doped chabazite particles toform a masterbatch as described above at a temperature of 160° C. Thezeolite and polymer addition rates were adjusted so as to result in afilm with around 2 wt % palladium-doped zeolite. The compounded mixturewas then extruded through a blown film line to produce multilayerstructures (20 μm), using the following conditions:

Inner layer (LDPE):

Extrusion speed: 25 rpm

Temperature profile from feeding zone to die adaptor (° C.): 30, 160,160, 160, 160

Middle layer (LDPE):

Extrusion speed: 25 rpm

Temperature profile from feeding zone to die adaptor (° C.): 30, 160,160, 160, 160

Outer layer (LDPE+absorbent):

Extrusion speed: 50 rpm

Temperature profile (° C.) from feeding zone to die: 30, 160, 160, 160,160, 160, 160 and 160

According to the film ash test results, the tested film had a zeoliteloading as follows:

Pd-Chabazite-2.08 wt %

Testing of Polymer Films

A series of experiments were conducted to evaluate the ethylene removalperformance of different palladium-doped zeolites to compare theirperformance after incorporation into the polymer film vs as a powder.

Ethylene Uptake Measurement

A film containing 0.208 g zeolite was prepared and placed into a sealed1990 ml jar. Ethylene gas was injected into the jar and reached 500 ppm.The inner atmosphere in the jar was analysed at regular intervals. Theconcentration of ethylene was determined by GC analysis. Temperature andhumidity in the jar were maintained at 5° C. and RH 90-95% during thetest.

Ethylene Uptake: The LDPE film and zeolite powder (control=1%Pd-chabazite powder) were tested for ethylene uptake as described above

Results

The ethylene removal performance of the LDPE multilayer film was shownin FIG. 3 . It was found the film retained around ca. 60-70% activity ofthe zeolite powder.

Example 4—Preparation and Testing of a Polymer Film with a PolymericCoating Incorporating Pd-Doped Chabazite Particles

An ink was prepared by the addition of polyvinylpyrrolidone (1 w %) to astirring suspension of 1% palladium-doped chabazite particles (10 wt %).The ink was sprayed onto a polyamide PA6 film (Xtend). The film was thendried using a hot plate (100° C.) for 10 minutes. The coating of thesubstrate was 0.25 g per 150 mm×150 mm of film. The particle size (D50)was 6.4 μm.

Ethylene Uptake: The coated film (coated Xtend) and 0.25 g zeolitepowder (control=1% Pd-chabazite powder) were tested for ethylene uptakeas described above.

Results: As shown in FIG. 4 the coated film removed the majority of theethylene with a significant reduction of the ethylene concentration inthe first 2 hours of the experiment.

What is claimed:
 1. A packaging material for the adsorption of volatile organic compounds, wherein the packaging material comprises a coating on its surface, and wherein the coating comprises a polymeric binder and particles of a palladium-doped zeolite with the CHA framework type.
 2. The packaging material according to claim 1, wherein the packaging material is a lid for a container.
 3. The packaging material according to claim 2, wherein the packaging material is a bottle lid.
 4. The packaging material according to claim 2, wherein the packaging material is a lid of a clamshell box.
 5. The packaging material according to claim 1, wherein the packaging material is a packaging insert.
 6. The packaging material according to claim 5, wherein the packaging material is a strip.
 7. The packaging material according to claim 5, wherein the packaging material is a strip comprising high-density spunbound polyethylene fibers.
 8. The packaging material according to claim 1, wherein the zeolite comprises 0.2 to 2 wt % palladium based on the total weight of doped zeolite.
 9. The packaging material according to claim 1, wherein the zeolite has a silica to alumina molar ratio (SAR) of less than or equal to 100:1.
 10. A packaging structure comprising the packaging material according to claim
 1. 